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"May" is pretty specious. Is there any evidence of something likely to work? I would love to see practical fusion, but I see no reason to believe it will exist

"May" is pretty specious. Is there any evidence of something likely to work? I would love to see practical fusion, but I see no reason to believe it will exist soon. Someone has to figure out how to actually make it practical first.

Tuna-Fish 5y ago
In magnetic confinement fusion, power density scales to the fourth power of the magnetic field strength. The only way to reasonably achieve the kind of magnetic fields needed without massive constant power draw is superconducting magnets. For a very long time, the best superconductors available limited the maximum field strength to ~ 5-6T. This limited the space of possible magnetic confinement reactors into basically ITER, or "big enough that you need a major multi-decade international collaboration to build it". Last decade, major discoveries were made in practical high-temperature superconductors. By 2017, you could commercially purchase superconducting tape that can do >8T, the state of the art has improved since, and keeps improving. All the constraints and limits on fusion that were known since the field began are changing now. Most importantly, with high-field magnets, the size of a theoretically functional net-energy fusion reactor comes way down, to what is achievably by a reasonably well funded startup. The whole field is open now, and all the different magnetic confinement fusion technologies that were tested and discarded over the first 60 years of fusion research are now being re-evaluated in ligth of the new magnets that are available. That's why there are now like a dozen well-funded fusion startups.
- SubiculumCode 5y ago
  Sounds like the story of deep learning once computing power cheapened.
- wiz21c 5y ago
  Do you mean that ITER could be obsolete before even reaching a production phase ?
  - neltnerb 5y ago
    Absolutely, as is the case in any huge project, it takes long enough to build that at some point you have to freeze the design and technology keeps progressing. It's hard to predict which pieces of technology will mature on what timeline, and at some point you just have to start. That ITER doesn't use superconducting magnets to me means that it will definitely be "obsolete" in the sense of using the most modern technologies, but it's still going to do the job it was designed for.
    - Tuna-Fish 5y ago
      Iter uses superconducting magnets. They are the best superconducting magnets that were available when the design was finalized in 1998. Modern ones are much better.
      - neltnerb 5y ago
        Sorry, yes, you're right, I meant modern ones.
  - Eelongate 5y ago
    It already is, they're still using Nb-Sn superconductors for ITER. The whole project is a manifestation of the sunk costs fallacy.
  - kortex 5y ago
    Yes and no. Yes in that the technology will be stale and there will be far superior materials science, electronics, etc, by the time it is online. No, in that its principle purpose is fusion and plasma research. It'll still be able to do science.
  - ncmncm 5y ago
    ITER is absolutely obsolete, in any sense requiring it to be a stop on the way to production. But it was never intended for that. ITER could, if ever completed, provide a wealth of research results on plasma confinement. But only that. And, it is likely to be too late to the party.
tim333 5y ago
Their current prototype, no 6, reached 100 million C. The next, prototype 7 they say should produce net electricity in 2023 or so. We'll see. That's not commercial electricity production but any production would be a step forward.

Tuna-Fish 5y ago

In magnetic confinement fusion, power density scales to the fourth power of the magnetic field strength. The only way to reasonably achieve the kind of magnetic fields needed without massive constant power draw is superconducting magnets. For a very long time, the best superconductors available limited the maximum field strength to ~ 5-6T. This limited the space of possible magnetic confinement reactors into basically ITER, or "big enough that you need a major multi-decade international collaboration to build it". Last decade, major discoveries were made in practical high-temperature superconductors. By 2017, you could commercially purchase superconducting tape that can do >8T, the state of the art has improved since, and keeps improving. All the constraints and limits on fusion that were known since the field began are changing now. Most importantly, with high-field magnets, the size of a theoretically functional net-energy fusion reactor comes way down, to what is achievably by a reasonably well funded startup. The whole field is open now, and all the different magnetic confinement fusion technologies that were tested and discarded over the first 60 years of fusion research are now being re-evaluated in ligth of the new magnets that are available. That's why there are now like a dozen well-funded fusion startups.

SubiculumCode 5y ago
Sounds like the story of deep learning once computing power cheapened.
wiz21c 5y ago
Do you mean that ITER could be obsolete before even reaching a production phase ?
- neltnerb 5y ago
  Absolutely, as is the case in any huge project, it takes long enough to build that at some point you have to freeze the design and technology keeps progressing. It's hard to predict which pieces of technology will mature on what timeline, and at some point you just have to start. That ITER doesn't use superconducting magnets to me means that it will definitely be "obsolete" in the sense of using the most modern technologies, but it's still going to do the job it was designed for.
  - Tuna-Fish 5y ago
    Iter uses superconducting magnets. They are the best superconducting magnets that were available when the design was finalized in 1998. Modern ones are much better.
    - neltnerb 5y ago
      Sorry, yes, you're right, I meant modern ones.
- Eelongate 5y ago
  It already is, they're still using Nb-Sn superconductors for ITER. The whole project is a manifestation of the sunk costs fallacy.
- kortex 5y ago
  Yes and no. Yes in that the technology will be stale and there will be far superior materials science, electronics, etc, by the time it is online. No, in that its principle purpose is fusion and plasma research. It'll still be able to do science.
- ncmncm 5y ago
  ITER is absolutely obsolete, in any sense requiring it to be a stop on the way to production. But it was never intended for that. ITER could, if ever completed, provide a wealth of research results on plasma confinement. But only that. And, it is likely to be too late to the party.

tim333 5y ago

Their current prototype, no 6, reached 100 million C. The next, prototype 7 they say should produce net electricity in 2023 or so. We'll see. That's not commercial electricity production but any production would be a step forward.